* [PATCH v3 1/9] vfs: add copy_file_range syscall and vfs helper
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 2/9] x86: add sys_copy_file_range to syscall tables Anna Schumaker
` (8 subsequent siblings)
9 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
From: Zach Brown <zab@redhat.com>
Add a copy_file_range() system call for offloading copies between
regular files.
This gives an interface to underlying layers of the storage stack which
can copy without reading and writing all the data. There are a few
candidates that should support copy offloading in the nearer term:
- btrfs shares extent references with its clone ioctl
- NFS has patches to add a COPY command which copies on the server
- SCSI has a family of XCOPY commands which copy in the device
This system call avoids the complexity of also accelerating the creation
of the destination file by operating on an existing destination file
descriptor, not a path.
Currently the high level vfs entry point limits copy offloading to files
on the same mount and super (and not in the same file). This can be
relaxed if we get implementations which can copy between file systems
safely.
Signed-off-by: Zach Brown <zab@redhat.com>
[Anna Schumaker: Change -EINVAL to -EBADF during file verification]
[Anna Schumaker: Change flags parameter from int to unsigned int]
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
v3:
- Change flags parameter to take an unsigned int instead of an int
---
fs/read_write.c | 129 ++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 3 +
include/uapi/asm-generic/unistd.h | 2 +
kernel/sys_ni.c | 1 +
4 files changed, 135 insertions(+)
diff --git a/fs/read_write.c b/fs/read_write.c
index 819ef3f..dd10750 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -16,6 +16,7 @@
#include <linux/pagemap.h>
#include <linux/splice.h>
#include <linux/compat.h>
+#include <linux/mount.h>
#include "internal.h"
#include <asm/uaccess.h>
@@ -1327,3 +1328,131 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
return do_sendfile(out_fd, in_fd, NULL, count, 0);
}
#endif
+
+/*
+ * copy_file_range() differs from regular file read and write in that it
+ * specifically allows return partial success. When it does so is up to
+ * the copy_file_range method.
+ */
+ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len, unsigned int flags)
+{
+ struct inode *inode_in;
+ struct inode *inode_out;
+ ssize_t ret;
+
+ if (flags)
+ return -EINVAL;
+
+ if (len == 0)
+ return 0;
+
+ /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
+ ret = rw_verify_area(READ, file_in, &pos_in, len);
+ if (ret >= 0)
+ ret = rw_verify_area(WRITE, file_out, &pos_out, len);
+ if (ret < 0)
+ return ret;
+
+ if (!(file_in->f_mode & FMODE_READ) ||
+ !(file_out->f_mode & FMODE_WRITE) ||
+ (file_out->f_flags & O_APPEND) ||
+ !file_in->f_op || !file_in->f_op->copy_file_range)
+ return -EBADF;
+
+ inode_in = file_inode(file_in);
+ inode_out = file_inode(file_out);
+
+ /* make sure offsets don't wrap and the input is inside i_size */
+ if (pos_in + len < pos_in || pos_out + len < pos_out ||
+ pos_in + len > i_size_read(inode_in))
+ return -EINVAL;
+
+ /* this could be relaxed once a method supports cross-fs copies */
+ if (inode_in->i_sb != inode_out->i_sb ||
+ file_in->f_path.mnt != file_out->f_path.mnt)
+ return -EXDEV;
+
+ /* forbid ranges in the same file */
+ if (inode_in == inode_out)
+ return -EINVAL;
+
+ ret = mnt_want_write_file(file_out);
+ if (ret)
+ return ret;
+
+ ret = file_in->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
+ len, flags);
+ if (ret > 0) {
+ fsnotify_access(file_in);
+ add_rchar(current, ret);
+ fsnotify_modify(file_out);
+ add_wchar(current, ret);
+ }
+ inc_syscr(current);
+ inc_syscw(current);
+
+ mnt_drop_write_file(file_out);
+
+ return ret;
+}
+EXPORT_SYMBOL(vfs_copy_file_range);
+
+SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
+ int, fd_out, loff_t __user *, off_out,
+ size_t, len, unsigned int, flags)
+{
+ loff_t pos_in;
+ loff_t pos_out;
+ struct fd f_in;
+ struct fd f_out;
+ ssize_t ret;
+
+ f_in = fdget(fd_in);
+ f_out = fdget(fd_out);
+ if (!f_in.file || !f_out.file) {
+ ret = -EBADF;
+ goto out;
+ }
+
+ ret = -EFAULT;
+ if (off_in) {
+ if (copy_from_user(&pos_in, off_in, sizeof(loff_t)))
+ goto out;
+ } else {
+ pos_in = f_in.file->f_pos;
+ }
+
+ if (off_out) {
+ if (copy_from_user(&pos_out, off_out, sizeof(loff_t)))
+ goto out;
+ } else {
+ pos_out = f_out.file->f_pos;
+ }
+
+ ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
+ flags);
+ if (ret > 0) {
+ pos_in += ret;
+ pos_out += ret;
+
+ if (off_in) {
+ if (copy_to_user(off_in, &pos_in, sizeof(loff_t)))
+ ret = -EFAULT;
+ } else {
+ f_in.file->f_pos = pos_in;
+ }
+
+ if (off_out) {
+ if (copy_to_user(off_out, &pos_out, sizeof(loff_t)))
+ ret = -EFAULT;
+ } else {
+ f_out.file->f_pos = pos_out;
+ }
+ }
+out:
+ fdput(f_in);
+ fdput(f_out);
+ return ret;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 72d8a84..6220307 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1642,6 +1642,7 @@ struct file_operations {
#ifndef CONFIG_MMU
unsigned (*mmap_capabilities)(struct file *);
#endif
+ ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
};
struct inode_operations {
@@ -1695,6 +1696,8 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
unsigned long, loff_t *);
extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
unsigned long, loff_t *);
+extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
+ loff_t, size_t, unsigned int);
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index ee12400..078bd21 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -713,6 +713,8 @@ __SC_COMP(__NR_execveat, sys_execveat, compat_sys_execveat)
__SYSCALL(__NR_userfaultfd, sys_userfaultfd)
#define __NR_membarrier 283
__SYSCALL(__NR_membarrier, sys_membarrier)
+#define __NR_copy_file_range 283
+__SYSCALL(__NR_copy_file_range, sys_copy_file_range)
#undef __NR_syscalls
#define __NR_syscalls 284
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index a02decf..83c5c82 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -174,6 +174,7 @@ cond_syscall(sys_setfsuid);
cond_syscall(sys_setfsgid);
cond_syscall(sys_capget);
cond_syscall(sys_capset);
+cond_syscall(sys_copy_file_range);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v3 2/9] x86: add sys_copy_file_range to syscall tables
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 1/9] vfs: add copy_file_range syscall and vfs helper Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 3/9] btrfs: add .copy_file_range file operation Anna Schumaker
` (7 subsequent siblings)
9 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
From: Zach Brown <zab@redhat.com>
Add sys_copy_file_range to the x86 syscall tables.
Signed-off-by: Zach Brown <zab@redhat.com>
[Anna Schumaker: Update syscall number in syscall_32.tbl]
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 7663c45..0531270 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -382,3 +382,4 @@
373 i386 shutdown sys_shutdown
374 i386 userfaultfd sys_userfaultfd
375 i386 membarrier sys_membarrier
+376 i386 copy_file_range sys_copy_file_range
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 278842f..03a9396 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -331,6 +331,7 @@
322 64 execveat stub_execveat
323 common userfaultfd sys_userfaultfd
324 common membarrier sys_membarrier
+325 common copy_file_range sys_copy_file_range
#
# x32-specific system call numbers start at 512 to avoid cache impact
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v3 3/9] btrfs: add .copy_file_range file operation
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 1/9] vfs: add copy_file_range syscall and vfs helper Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 2/9] x86: add sys_copy_file_range to syscall tables Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 4/9] vfs: Copy should check len after file open mode Anna Schumaker
` (6 subsequent siblings)
9 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
From: Zach Brown <zab@redhat.com>
This rearranges the existing COPY_RANGE ioctl implementation so that the
.copy_file_range file operation can call the core loop that copies file
data extent items.
The extent copying loop is lifted up into its own function. It retains
the core btrfs error checks that should be shared.
Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/ctree.h | 3 ++
fs/btrfs/file.c | 1 +
fs/btrfs/ioctl.c | 91 ++++++++++++++++++++++++++++++++------------------------
3 files changed, 56 insertions(+), 39 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 938efe3..5d06a4f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3996,6 +3996,9 @@ int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
loff_t pos, size_t write_bytes,
struct extent_state **cached);
int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end);
+ssize_t btrfs_copy_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len, int flags);
/* tree-defrag.c */
int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index b823fac..b05449c 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2816,6 +2816,7 @@ const struct file_operations btrfs_file_operations = {
#ifdef CONFIG_COMPAT
.compat_ioctl = btrfs_ioctl,
#endif
+ .copy_file_range = btrfs_copy_file_range,
};
void btrfs_auto_defrag_exit(void)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0adf542..4311554 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3727,17 +3727,16 @@ out:
return ret;
}
-static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
- u64 off, u64 olen, u64 destoff)
+static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
+ u64 off, u64 olen, u64 destoff)
{
struct inode *inode = file_inode(file);
+ struct inode *src = file_inode(file_src);
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct fd src_file;
- struct inode *src;
int ret;
u64 len = olen;
u64 bs = root->fs_info->sb->s_blocksize;
- int same_inode = 0;
+ int same_inode = src == inode;
/*
* TODO:
@@ -3750,49 +3749,20 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
* be either compressed or non-compressed.
*/
- /* the destination must be opened for writing */
- if (!(file->f_mode & FMODE_WRITE) || (file->f_flags & O_APPEND))
- return -EINVAL;
-
if (btrfs_root_readonly(root))
return -EROFS;
- ret = mnt_want_write_file(file);
- if (ret)
- return ret;
-
- src_file = fdget(srcfd);
- if (!src_file.file) {
- ret = -EBADF;
- goto out_drop_write;
- }
-
- ret = -EXDEV;
- if (src_file.file->f_path.mnt != file->f_path.mnt)
- goto out_fput;
-
- src = file_inode(src_file.file);
-
- ret = -EINVAL;
- if (src == inode)
- same_inode = 1;
-
- /* the src must be open for reading */
- if (!(src_file.file->f_mode & FMODE_READ))
- goto out_fput;
+ if (file_src->f_path.mnt != file->f_path.mnt ||
+ src->i_sb != inode->i_sb)
+ return -EXDEV;
/* don't make the dst file partly checksummed */
if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) !=
(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM))
- goto out_fput;
+ return -EINVAL;
- ret = -EISDIR;
if (S_ISDIR(src->i_mode) || S_ISDIR(inode->i_mode))
- goto out_fput;
-
- ret = -EXDEV;
- if (src->i_sb != inode->i_sb)
- goto out_fput;
+ return -EISDIR;
if (!same_inode) {
btrfs_double_inode_lock(src, inode);
@@ -3869,6 +3839,49 @@ out_unlock:
btrfs_double_inode_unlock(src, inode);
else
mutex_unlock(&src->i_mutex);
+ return ret;
+}
+
+ssize_t btrfs_copy_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len, int flags)
+{
+ ssize_t ret;
+
+ ret = btrfs_clone_files(file_out, file_in, pos_in, len, pos_out);
+ if (ret == 0)
+ ret = len;
+ return ret;
+}
+
+static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
+ u64 off, u64 olen, u64 destoff)
+{
+ struct fd src_file;
+ int ret;
+
+ /* the destination must be opened for writing */
+ if (!(file->f_mode & FMODE_WRITE) || (file->f_flags & O_APPEND))
+ return -EINVAL;
+
+ ret = mnt_want_write_file(file);
+ if (ret)
+ return ret;
+
+ src_file = fdget(srcfd);
+ if (!src_file.file) {
+ ret = -EBADF;
+ goto out_drop_write;
+ }
+
+ /* the src must be open for reading */
+ if (!(src_file.file->f_mode & FMODE_READ)) {
+ ret = -EINVAL;
+ goto out_fput;
+ }
+
+ ret = btrfs_clone_files(file, src_file.file, off, olen, destoff);
+
out_fput:
fdput(src_file);
out_drop_write:
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v3 4/9] vfs: Copy should check len after file open mode
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
` (2 preceding siblings ...)
2015-09-25 20:48 ` [PATCH v3 3/9] btrfs: add .copy_file_range file operation Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 5/9] vfs: Copy shouldn't forbid ranges inside the same file Anna Schumaker
` (5 subsequent siblings)
9 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
I don't think it makes sense to report that a copy succeeded if the
files aren't open properly.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
fs/read_write.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index dd10750..f3d6c48 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1345,9 +1345,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (flags)
return -EINVAL;
- if (len == 0)
- return 0;
-
/* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
ret = rw_verify_area(READ, file_in, &pos_in, len);
if (ret >= 0)
@@ -1378,6 +1375,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (inode_in == inode_out)
return -EINVAL;
+ if (len == 0)
+ return 0;
+
ret = mnt_want_write_file(file_out);
if (ret)
return ret;
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v3 5/9] vfs: Copy shouldn't forbid ranges inside the same file
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
` (3 preceding siblings ...)
2015-09-25 20:48 ` [PATCH v3 4/9] vfs: Copy should check len after file open mode Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-28 18:46 ` Darrick J. Wong
[not found] ` <1443214096-12769-1-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
` (4 subsequent siblings)
9 siblings, 1 reply; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
This is perfectly valid for BTRFS and XFS, so let's leave this up to
filesystems to check.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
fs/read_write.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index f3d6c48..8e7cb33 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1371,10 +1371,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
file_in->f_path.mnt != file_out->f_path.mnt)
return -EXDEV;
- /* forbid ranges in the same file */
- if (inode_in == inode_out)
- return -EINVAL;
-
if (len == 0)
return 0;
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH v3 5/9] vfs: Copy shouldn't forbid ranges inside the same file
2015-09-25 20:48 ` [PATCH v3 5/9] vfs: Copy shouldn't forbid ranges inside the same file Anna Schumaker
@ 2015-09-28 18:46 ` Darrick J. Wong
0 siblings, 0 replies; 19+ messages in thread
From: Darrick J. Wong @ 2015-09-28 18:46 UTC (permalink / raw)
To: Anna Schumaker
Cc: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
mtk.manpages, andros, hch
On Fri, Sep 25, 2015 at 04:48:11PM -0400, Anna Schumaker wrote:
> This is perfectly valid for BTRFS and XFS, so let's leave this up to
> filesystems to check.
>
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
--D
> ---
> fs/read_write.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index f3d6c48..8e7cb33 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1371,10 +1371,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> file_in->f_path.mnt != file_out->f_path.mnt)
> return -EXDEV;
>
> - /* forbid ranges in the same file */
> - if (inode_in == inode_out)
> - return -EINVAL;
> -
> if (len == 0)
> return 0;
>
> --
> 2.5.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-api" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 19+ messages in thread
[parent not found: <1443214096-12769-1-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>]
* [PATCH v3 6/9] vfs: Copy should use file_out rather than file_in
[not found] ` <1443214096-12769-1-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
@ 2015-09-25 20:48 ` Anna Schumaker
0 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs-u79uwXL29TY76Z2rM5mHXA,
linux-btrfs-u79uwXL29TY76Z2rM5mHXA,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA,
linux-api-u79uwXL29TY76Z2rM5mHXA, zab-ugsP4Wv/S6ZeoWH0uzbU5w,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn, clm-b10kYP2dOMg,
darrick.wong-QHcLZuEGTsvQT0dZR+AlfA,
mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w,
andros-HgOvQuBEEgTQT0dZR+AlfA, hch-wEGCiKHe2LqWVfeAwA7xHQ
The way to think about this is that the destination filesystem reads the
data from the source file and processes it accordingly. This is
especially important to avoid an infinate loop when doing a "server to
server" copy on NFS.
Signed-off-by: Anna Schumaker <Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
---
fs/read_write.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 8e7cb33..6f74f1f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1355,7 +1355,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (!(file_in->f_mode & FMODE_READ) ||
!(file_out->f_mode & FMODE_WRITE) ||
(file_out->f_flags & O_APPEND) ||
- !file_in->f_op || !file_in->f_op->copy_file_range)
+ !file_out->f_op || !file_out->f_op->copy_file_range)
return -EBADF;
inode_in = file_inode(file_in);
@@ -1378,8 +1378,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (ret)
return ret;
- ret = file_in->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
- len, flags);
+ ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
+ len, flags);
if (ret > 0) {
fsnotify_access(file_in);
add_rchar(current, ret);
--
2.5.3
--
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^ permalink raw reply related [flat|nested] 19+ messages in thread
* [PATCH v3 7/9] vfs: Remove copy_file_range mountpoint checks
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
` (5 preceding siblings ...)
[not found] ` <1443214096-12769-1-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice Anna Schumaker
` (2 subsequent siblings)
9 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
I still want to do an in-kernel copy even if the files are on different
mountpoints, and NFS has a "server to server" copy that expects two
files on different mountpoints. Let's have individual filesystems
implement this check instead.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
fs/read_write.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 6f74f1f..ee9fa37 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1366,11 +1366,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
pos_in + len > i_size_read(inode_in))
return -EINVAL;
- /* this could be relaxed once a method supports cross-fs copies */
- if (inode_in->i_sb != inode_out->i_sb ||
- file_in->f_path.mnt != file_out->f_path.mnt)
- return -EXDEV;
-
if (len == 0)
return 0;
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
` (6 preceding siblings ...)
2015-09-25 20:48 ` [PATCH v3 7/9] vfs: Remove copy_file_range mountpoint checks Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
[not found] ` <1443214096-12769-9-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-26 0:14 ` Andy Lutomirski
2015-09-25 20:48 ` [PATCH v3 9/9] btrfs: btrfs_copy_file_range() only supports reflinks Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 10/9] copy_file_range.2: New page documenting copy_file_range() Anna Schumaker
9 siblings, 2 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
The NFS server will need some kind offallback for filesystems that don't
have any kind of copy acceleration, and it should be generally useful to
have an in-kernel copy to avoid lots of switches between kernel and user
space.
I make this configurable by adding two new flags. Users who only want a
reflink can pass COPY_FR_REFLINK, and users who want a full data copy can
pass COPY_FR_COPY. The default (flags=0) means to first attempt a
reflink, but use the pagecache if that fails.
I moved the rw_verify_area() calls into the fallback code since some
filesystems can handle reflinking a large range.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
v3:
- Check that both filesystems have the same filesystem type
- Add COPY_FR_DEDUPE flag for Darrick
- Check that at most one flag is set at a time
---
fs/read_write.c | 61 +++++++++++++++++++++++++++++++----------------
include/linux/copy.h | 6 +++++
include/uapi/linux/Kbuild | 1 +
include/uapi/linux/copy.h | 8 +++++++
4 files changed, 56 insertions(+), 20 deletions(-)
create mode 100644 include/linux/copy.h
create mode 100644 include/uapi/linux/copy.h
diff --git a/fs/read_write.c b/fs/read_write.c
index ee9fa37..a0fd9dc 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -7,6 +7,7 @@
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
+#include <linux/copy.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fsnotify.h>
@@ -1329,6 +1330,29 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
}
#endif
+static ssize_t vfs_copy_file_pagecache(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len)
+{
+ ssize_t ret;
+
+ ret = rw_verify_area(READ, file_in, &pos_in, len);
+ if (ret >= 0) {
+ len = ret;
+ ret = rw_verify_area(WRITE, file_out, &pos_out, len);
+ if (ret >= 0)
+ len = ret;
+ }
+ if (ret < 0)
+ return ret;
+
+ file_start_write(file_out);
+ ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out, len, 0);
+ file_end_write(file_out);
+
+ return ret;
+}
+
/*
* copy_file_range() differs from regular file read and write in that it
* specifically allows return partial success. When it does so is up to
@@ -1338,34 +1362,26 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
struct file *file_out, loff_t pos_out,
size_t len, unsigned int flags)
{
- struct inode *inode_in;
- struct inode *inode_out;
ssize_t ret;
- if (flags)
+ /* Flags should only be used exclusively. */
+ if ((flags & COPY_FR_COPY) && (flags & ~COPY_FR_COPY))
return -EINVAL;
+ if ((flags & COPY_FR_REFLINK) && (flags & ~COPY_FR_REFLINK))
+ return -EINVAL;
+ if (flags & COPY_FR_DEDUPE)
+ return -EOPNOTSUPP;
- /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
- ret = rw_verify_area(READ, file_in, &pos_in, len);
- if (ret >= 0)
- ret = rw_verify_area(WRITE, file_out, &pos_out, len);
- if (ret < 0)
- return ret;
+ /* Default behavior is to try both. */
+ if (flags == 0)
+ flags = COPY_FR_COPY | COPY_FR_REFLINK;
if (!(file_in->f_mode & FMODE_READ) ||
!(file_out->f_mode & FMODE_WRITE) ||
(file_out->f_flags & O_APPEND) ||
- !file_out->f_op || !file_out->f_op->copy_file_range)
+ !file_out->f_op)
return -EBADF;
- inode_in = file_inode(file_in);
- inode_out = file_inode(file_out);
-
- /* make sure offsets don't wrap and the input is inside i_size */
- if (pos_in + len < pos_in || pos_out + len < pos_out ||
- pos_in + len > i_size_read(inode_in))
- return -EINVAL;
-
if (len == 0)
return 0;
@@ -1373,8 +1389,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
if (ret)
return ret;
- ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
- len, flags);
+ ret = -EOPNOTSUPP;
+ if (file_out->f_op->copy_file_range && (file_in->f_op == file_out->f_op))
+ ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
+ pos_out, len, flags);
+ if ((ret < 0) && (flags & COPY_FR_COPY))
+ ret = vfs_copy_file_pagecache(file_in, pos_in, file_out,
+ pos_out, len);
if (ret > 0) {
fsnotify_access(file_in);
add_rchar(current, ret);
diff --git a/include/linux/copy.h b/include/linux/copy.h
new file mode 100644
index 0000000..fd54543
--- /dev/null
+++ b/include/linux/copy.h
@@ -0,0 +1,6 @@
+#ifndef _LINUX_COPY_H
+#define _LINUX_COPY_H
+
+#include <uapi/linux/copy.h>
+
+#endif /* _LINUX_COPY_H */
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index f7b2db4..faafd67 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -90,6 +90,7 @@ header-y += coda_psdev.h
header-y += coff.h
header-y += connector.h
header-y += const.h
+header-y += copy.h
header-y += cramfs_fs.h
header-y += cuda.h
header-y += cyclades.h
diff --git a/include/uapi/linux/copy.h b/include/uapi/linux/copy.h
new file mode 100644
index 0000000..6225838
--- /dev/null
+++ b/include/uapi/linux/copy.h
@@ -0,0 +1,8 @@
+#ifndef _UAPI_LINUX_COPY_H
+#define _UAPI_LINUX_COPY_H
+
+#define COPY_FR_COPY (1 << 0) /* Only do a pagecache copy. */
+#define COPY_FR_REFLINK (1 << 1) /* Only make a reflink. */
+#define COPY_FR_DEDUPE (1 << 2) /* Deduplicate file data. */
+
+#endif /* _UAPI_LINUX_COPY_H */
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread[parent not found: <1443214096-12769-9-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>]
* Re: [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice
[not found] ` <1443214096-12769-9-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
@ 2015-09-25 21:58 ` Pádraig Brady
2015-09-28 18:31 ` Darrick J. Wong
1 sibling, 0 replies; 19+ messages in thread
From: Pádraig Brady @ 2015-09-25 21:58 UTC (permalink / raw)
To: Anna Schumaker, linux-nfs-u79uwXL29TY76Z2rM5mHXA,
linux-btrfs-u79uwXL29TY76Z2rM5mHXA,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA,
linux-api-u79uwXL29TY76Z2rM5mHXA, zab-ugsP4Wv/S6ZeoWH0uzbU5w,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn, clm-b10kYP2dOMg,
darrick.wong-QHcLZuEGTsvQT0dZR+AlfA,
mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w,
andros-HgOvQuBEEgTQT0dZR+AlfA, hch-wEGCiKHe2LqWVfeAwA7xHQ
On 25/09/15 21:48, Anna Schumaker wrote:
> The NFS server will need some kind offallback for filesystems that don't
> have any kind of copy acceleration, and it should be generally useful to
> have an in-kernel copy to avoid lots of switches between kernel and user
> space.
>
> I make this configurable by adding two new flags. Users who only want a
> reflink can pass COPY_FR_REFLINK, and users who want a full data copy can
> pass COPY_FR_COPY. The default (flags=0) means to first attempt a
> reflink, but use the pagecache if that fails.
>
> I moved the rw_verify_area() calls into the fallback code since some
> filesystems can handle reflinking a large range.
>
> Signed-off-by: Anna Schumaker <Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
Reviewed-by: Pádraig Brady <P@draigBrady.com>
LGTM. For my reference, for cp(1), mv(1), install(1), this will avoid
user space copies in the normal case, client side copies in the network
file system case, and provide a more generalized interface to reflink().
coreutils pseudo code is:
unsigned int cfr_flags = COPY_FR_COPY;
if (mode == mv)
cfr_flags = 0; /* reflink falling back to normal */
else if (mode == cp) {
if --reflink || --reflink==always
cfr_flags = COPY_FR_REFLINK;
else if --reflink==auto
cfr_flags = 0; /* reflink falling back to normal */
}
if vfs_copy_file_range(..., cfr_flags) == ENOTSUP
normal_user_space_copy();
thanks,
Pádraig.
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice
[not found] ` <1443214096-12769-9-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
2015-09-25 21:58 ` Pádraig Brady
@ 2015-09-28 18:31 ` Darrick J. Wong
[not found] ` <20150928183152.GB850-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
1 sibling, 1 reply; 19+ messages in thread
From: Darrick J. Wong @ 2015-09-28 18:31 UTC (permalink / raw)
To: Anna Schumaker
Cc: linux-nfs-u79uwXL29TY76Z2rM5mHXA,
linux-btrfs-u79uwXL29TY76Z2rM5mHXA,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA,
linux-api-u79uwXL29TY76Z2rM5mHXA, zab-ugsP4Wv/S6ZeoWH0uzbU5w,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn, clm-b10kYP2dOMg,
mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w,
andros-HgOvQuBEEgTQT0dZR+AlfA, hch-wEGCiKHe2LqWVfeAwA7xHQ
On Fri, Sep 25, 2015 at 04:48:14PM -0400, Anna Schumaker wrote:
> The NFS server will need some kind offallback for filesystems that don't
"some kind of fallback"
> have any kind of copy acceleration, and it should be generally useful to
> have an in-kernel copy to avoid lots of switches between kernel and user
> space.
>
> I make this configurable by adding two new flags. Users who only want a
> reflink can pass COPY_FR_REFLINK, and users who want a full data copy can
> pass COPY_FR_COPY. The default (flags=0) means to first attempt a
> reflink, but use the pagecache if that fails.
"The COPY_FR_DEDUPE flag makes a reflink, but only if the contents of both
file ranges are identical."
> I moved the rw_verify_area() calls into the fallback code since some
> filesystems can handle reflinking a large range.
>
> Signed-off-by: Anna Schumaker <Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
> ---
> v3:
> - Check that both filesystems have the same filesystem type
> - Add COPY_FR_DEDUPE flag for Darrick
> - Check that at most one flag is set at a time
> ---
> fs/read_write.c | 61 +++++++++++++++++++++++++++++++----------------
> include/linux/copy.h | 6 +++++
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/copy.h | 8 +++++++
> 4 files changed, 56 insertions(+), 20 deletions(-)
> create mode 100644 include/linux/copy.h
> create mode 100644 include/uapi/linux/copy.h
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index ee9fa37..a0fd9dc 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -7,6 +7,7 @@
> #include <linux/slab.h>
> #include <linux/stat.h>
> #include <linux/fcntl.h>
> +#include <linux/copy.h>
> #include <linux/file.h>
> #include <linux/uio.h>
> #include <linux/fsnotify.h>
> @@ -1329,6 +1330,29 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
> }
> #endif
>
> +static ssize_t vfs_copy_file_pagecache(struct file *file_in, loff_t pos_in,
> + struct file *file_out, loff_t pos_out,
> + size_t len)
> +{
> + ssize_t ret;
> +
> + ret = rw_verify_area(READ, file_in, &pos_in, len);
> + if (ret >= 0) {
> + len = ret;
> + ret = rw_verify_area(WRITE, file_out, &pos_out, len);
> + if (ret >= 0)
> + len = ret;
> + }
> + if (ret < 0)
> + return ret;
> +
> + file_start_write(file_out);
> + ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out, len, 0);
> + file_end_write(file_out);
> +
> + return ret;
> +}
> +
> /*
> * copy_file_range() differs from regular file read and write in that it
> * specifically allows return partial success. When it does so is up to
> @@ -1338,34 +1362,26 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> size_t len, unsigned int flags)
> {
> - struct inode *inode_in;
> - struct inode *inode_out;
> ssize_t ret;
>
> - if (flags)
> + /* Flags should only be used exclusively. */
> + if ((flags & COPY_FR_COPY) && (flags & ~COPY_FR_COPY))
> return -EINVAL;
> + if ((flags & COPY_FR_REFLINK) && (flags & ~COPY_FR_REFLINK))
> + return -EINVAL;
> + if (flags & COPY_FR_DEDUPE)
> + return -EOPNOTSUPP;
Since dedupe can't be combined with copy or reflink either, we might as well
say:
if ((flags & COPY_FR_DEDUPE) && (flags & ~COPY_FR_DEDUPE))
return -EINVAL;
and let the per-fs copy_file_range()s dispatch appropriately.
Otherwise, you can add:
Reviewed-by: Darrick J. Wong <darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
--D
>
> - /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */
> - ret = rw_verify_area(READ, file_in, &pos_in, len);
> - if (ret >= 0)
> - ret = rw_verify_area(WRITE, file_out, &pos_out, len);
> - if (ret < 0)
> - return ret;
> + /* Default behavior is to try both. */
> + if (flags == 0)
> + flags = COPY_FR_COPY | COPY_FR_REFLINK;
>
> if (!(file_in->f_mode & FMODE_READ) ||
> !(file_out->f_mode & FMODE_WRITE) ||
> (file_out->f_flags & O_APPEND) ||
> - !file_out->f_op || !file_out->f_op->copy_file_range)
> + !file_out->f_op)
> return -EBADF;
>
> - inode_in = file_inode(file_in);
> - inode_out = file_inode(file_out);
> -
> - /* make sure offsets don't wrap and the input is inside i_size */
> - if (pos_in + len < pos_in || pos_out + len < pos_out ||
> - pos_in + len > i_size_read(inode_in))
> - return -EINVAL;
> -
> if (len == 0)
> return 0;
>
> @@ -1373,8 +1389,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> if (ret)
> return ret;
>
> - ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,
> - len, flags);
> + ret = -EOPNOTSUPP;
> + if (file_out->f_op->copy_file_range && (file_in->f_op == file_out->f_op))
> + ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
> + pos_out, len, flags);
> + if ((ret < 0) && (flags & COPY_FR_COPY))
> + ret = vfs_copy_file_pagecache(file_in, pos_in, file_out,
> + pos_out, len);
> if (ret > 0) {
> fsnotify_access(file_in);
> add_rchar(current, ret);
> diff --git a/include/linux/copy.h b/include/linux/copy.h
> new file mode 100644
> index 0000000..fd54543
> --- /dev/null
> +++ b/include/linux/copy.h
> @@ -0,0 +1,6 @@
> +#ifndef _LINUX_COPY_H
> +#define _LINUX_COPY_H
> +
> +#include <uapi/linux/copy.h>
> +
> +#endif /* _LINUX_COPY_H */
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index f7b2db4..faafd67 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -90,6 +90,7 @@ header-y += coda_psdev.h
> header-y += coff.h
> header-y += connector.h
> header-y += const.h
> +header-y += copy.h
> header-y += cramfs_fs.h
> header-y += cuda.h
> header-y += cyclades.h
> diff --git a/include/uapi/linux/copy.h b/include/uapi/linux/copy.h
> new file mode 100644
> index 0000000..6225838
> --- /dev/null
> +++ b/include/uapi/linux/copy.h
> @@ -0,0 +1,8 @@
> +#ifndef _UAPI_LINUX_COPY_H
> +#define _UAPI_LINUX_COPY_H
> +
> +#define COPY_FR_COPY (1 << 0) /* Only do a pagecache copy. */
> +#define COPY_FR_REFLINK (1 << 1) /* Only make a reflink. */
> +#define COPY_FR_DEDUPE (1 << 2) /* Deduplicate file data. */
> +
> +#endif /* _UAPI_LINUX_COPY_H */
> --
> 2.5.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-api" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 19+ messages in thread
* Re: [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice
2015-09-25 20:48 ` [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice Anna Schumaker
[not found] ` <1443214096-12769-9-git-send-email-Anna.Schumaker-ZwjVKphTwtPQT0dZR+AlfA@public.gmane.org>
@ 2015-09-26 0:14 ` Andy Lutomirski
2015-09-28 14:28 ` Anna Schumaker
1 sibling, 1 reply; 19+ messages in thread
From: Andy Lutomirski @ 2015-09-26 0:14 UTC (permalink / raw)
To: Anna Schumaker
Cc: linux-nfs, Linux btrfs Developers List, Linux FS Devel, Linux API,
Zach Brown, Al Viro, Chris Mason, Darrick J. Wong,
Michael Kerrisk-manpages, andros, Christoph Hellwig
On Fri, Sep 25, 2015 at 1:48 PM, Anna Schumaker
<Anna.Schumaker@netapp.com> wrote:
> The NFS server will need some kind offallback for filesystems that don't
> have any kind of copy acceleration, and it should be generally useful to
> have an in-kernel copy to avoid lots of switches between kernel and user
> space.
>
> I make this configurable by adding two new flags. Users who only want a
> reflink can pass COPY_FR_REFLINK, and users who want a full data copy can
> pass COPY_FR_COPY. The default (flags=0) means to first attempt a
> reflink, but use the pagecache if that fails.
>
Can you clarify how the subject line fits in? I'm a bit lost.
--Andy
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice
2015-09-26 0:14 ` Andy Lutomirski
@ 2015-09-28 14:28 ` Anna Schumaker
0 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-28 14:28 UTC (permalink / raw)
To: Andy Lutomirski
Cc: linux-nfs, Linux btrfs Developers List, Linux FS Devel, Linux API,
Zach Brown, Al Viro, Chris Mason, Darrick J. Wong,
Michael Kerrisk-manpages, andros, Christoph Hellwig
On 09/25/2015 08:14 PM, Andy Lutomirski wrote:
> On Fri, Sep 25, 2015 at 1:48 PM, Anna Schumaker
> <Anna.Schumaker@netapp.com> wrote:
>> The NFS server will need some kind offallback for filesystems that don't
>> have any kind of copy acceleration, and it should be generally useful to
>> have an in-kernel copy to avoid lots of switches between kernel and user
>> space.
>>
>> I make this configurable by adding two new flags. Users who only want a
>> reflink can pass COPY_FR_REFLINK, and users who want a full data copy can
>> pass COPY_FR_COPY. The default (flags=0) means to first attempt a
>> reflink, but use the pagecache if that fails.
>>
>
> Can you clarify how the subject line fits in? I'm a bit lost.
I'll try! I use the splice interface to copy file data from the pagecache, and this implements an in-kernel copy that can be controlled using the two flags I added.
I plan on using this in the NFS server when I add server-side copy support.
Let me know if that doesn't answer your question!
Anna
>
> --Andy
>
^ permalink raw reply [flat|nested] 19+ messages in thread
* [PATCH v3 9/9] btrfs: btrfs_copy_file_range() only supports reflinks
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
` (7 preceding siblings ...)
2015-09-25 20:48 ` [PATCH v3 8/9] vfs: copy_file_range() can do a pagecache copy with splice Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-25 20:48 ` [PATCH v3 10/9] copy_file_range.2: New page documenting copy_file_range() Anna Schumaker
9 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
Reject copies that don't have the COPY_FR_REFLINK flag set.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/ioctl.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4311554..2e14b91 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -44,6 +44,7 @@
#include <linux/uuid.h>
#include <linux/btrfs.h>
#include <linux/uaccess.h>
+#include <linux/copy.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
@@ -3848,6 +3849,9 @@ ssize_t btrfs_copy_file_range(struct file *file_in, loff_t pos_in,
{
ssize_t ret;
+ if (!(flags & COPY_FR_REFLINK))
+ return -EOPNOTSUPP;
+
ret = btrfs_clone_files(file_out, file_in, pos_in, len, pos_out);
if (ret == 0)
ret = len;
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* [PATCH v3 10/9] copy_file_range.2: New page documenting copy_file_range()
2015-09-25 20:48 [PATCH v3 0/9] VFS: In-kernel copy system call Anna Schumaker
` (8 preceding siblings ...)
2015-09-25 20:48 ` [PATCH v3 9/9] btrfs: btrfs_copy_file_range() only supports reflinks Anna Schumaker
@ 2015-09-25 20:48 ` Anna Schumaker
2015-09-28 18:40 ` Darrick J. Wong
9 siblings, 1 reply; 19+ messages in thread
From: Anna Schumaker @ 2015-09-25 20:48 UTC (permalink / raw)
To: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
darrick.wong, mtk.manpages, andros, hch
copy_file_range() is a new system call for copying ranges of data
completely in the kernel. This gives filesystems an opportunity to
implement some kind of "copy acceleration", such as reflinks or
server-side-copy (in the case of NFS).
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
v3:
- Added license information
- Updated splice(2)
- Various other edits after mailing list discussion
---
man2/copy_file_range.2 | 211 +++++++++++++++++++++++++++++++++++++++++++++++++
man2/splice.2 | 1 +
2 files changed, 212 insertions(+)
create mode 100644 man2/copy_file_range.2
diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2
new file mode 100644
index 0000000..6d66d4a
--- /dev/null
+++ b/man2/copy_file_range.2
@@ -0,0 +1,211 @@
+.\"This manpage is Copyright (C) 2015 Anna Schumaker <Anna.Schumaker@Netapp.com>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of
+.\" this manual under the conditions for verbatim copying, provided that
+.\" the entire resulting derived work is distributed under the terms of
+.\" a permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume.
+.\" no responsibility for errors or omissions, or for damages resulting.
+.\" from the use of the information contained herein. The author(s) may.
+.\" not have taken the same level of care in the production of this.
+.\" manual, which is licensed free of charge, as they might when working.
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.TH COPY 2 2015-08-31 "Linux" "Linux Programmer's Manual"
+.SH NAME
+copy_file_range \- Copy a range of data from one file to another
+.SH SYNOPSIS
+.nf
+.B #include <linux/copy.h>
+.B #include <sys/syscall.h>
+.B #include <unistd.h>
+
+.BI "ssize_t copy_file_range(int " fd_in ", loff_t *" off_in ", int " fd_out ",
+.BI " loff_t *" off_out ", size_t " len \
+", unsigned int " flags );
+.fi
+.SH DESCRIPTION
+The
+.BR copy_file_range ()
+system call performs an in-kernel copy between two file descriptors
+without the additional cost of transferring data from the kernel to userspace
+and then back into the kernel.
+It copies up to
+.I len
+bytes of data from file descriptor
+.I fd_in
+to file descriptor
+.IR fd_out ,
+overwriting any data that exists within the requested range of the target file.
+
+The following semantics apply for
+.IR off_in ,
+and similar statements apply to
+.IR off_out :
+.IP * 3
+If
+.I off_in
+is NULL, then bytes are read from
+.I fd_in
+starting from the current file offset, and the offset is
+adjusted by the number of bytes copied.
+.IP *
+If
+.I off_in
+is not NULL, then
+.I off_in
+must point to a buffer that specifies the starting
+offset where bytes from
+.I fd_in
+will be read. The current file offset of
+.I fd_in
+is not changed, but
+.I off_in
+is adjusted appropriately.
+.PP
+
+The
+.I flags
+argument can have one of the following flags set:
+.TP 1.9i
+.B COPY_FR_COPY
+Copy all the file data in the requested range.
+Some filesystems might be able to accelerate this copy
+to avoid unnecessary data transfers.
+.TP
+.B COPY_FR_REFLINK
+Create a lightweight "reflink", where data is not copied until
+one of the files is modified.
+.PP
+The default behavior
+.RI ( flags
+== 0) is to try creating a reflink,
+and if reflinking fails
+.BR copy_file_range ()
+will fall back to performing a full data copy.
+.SH RETURN VALUE
+Upon successful completion,
+.BR copy_file_range ()
+will return the number of bytes copied between files.
+This could be less than the length originally requested.
+
+On error,
+.BR copy_file_range ()
+returns \-1 and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EBADF
+One or more file descriptors are not valid; or
+.I fd_in
+is not open for reading; or
+.I fd_out
+is not open for writing.
+.TP
+.B EINVAL
+Requested range extends beyond the end of the source file; or the
+.I flags
+argument is set to an invalid value.
+.TP
+.B EIO
+A low level I/O error occurred while copying.
+.TP
+.B ENOMEM
+Out of memory.
+.TP
+.B ENOSPC
+There is not enough space on the target filesystem to complete the copy.
+.TP
+.B EOPNOTSUPP
+.B COPY_REFLINK
+was specified in
+.IR flags ,
+but the target filesystem does not support reflinks.
+.TP
+.B EXDEV
+Target filesystem doesn't support cross-filesystem copies.
+.SH VERSIONS
+The
+.BR copy_file_range ()
+system call first appeared in Linux 4.4.
+.SH CONFORMING TO
+The
+.BR copy_file_range ()
+system call is a nonstandard Linux extension.
+.SH EXAMPLE
+.nf
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <linux/copy.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+loff_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
+ loff_t *off_out, size_t len, unsigned int flags)
+{
+ return syscall(__NR_copy_file_range, fd_in, off_in, fd_out,
+ off_out, len, flags);
+}
+
+int main(int argc, char **argv)
+{
+ int fd_in, fd_out;
+ struct stat stat;
+ loff_t len, ret;
+ char buf[2];
+
+ if (argc != 3) {
+ fprintf(stderr, "Usage: %s <source> <destination>\\n", argv[0]);
+ exit(EXIT_FAILURE);
+ }
+
+ fd_in = open(argv[1], O_RDONLY);
+ if (fd_in == \-1) {
+ perror("open (argv[1])");
+ exit(EXIT_FAILURE);
+ }
+
+ if (fstat(fd_in, &stat) == \-1) {
+ perror("fstat");
+ exit(EXIT_FAILURE);
+ }
+ len = stat.st_size;
+
+ fd_out = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC, 0644);
+ if (fd_out == \-1) {
+ perror("open (argv[2])");
+ exit(EXIT_FAILURE);
+ }
+
+ do {
+ ret = copy_file_range(fd_in, NULL, fd_out, NULL, len, COPY_FR_COPY);
+ if (ret == \-1) {
+ perror("copy_file_range");
+ exit(EXIT_FAILURE);
+ }
+
+ len \-= ret;
+ } while (len > 0);
+
+ close(fd_in);
+ close(fd_out);
+ exit(EXIT_SUCCESS);
+}
+.fi
+.SH SEE ALSO
+.BR splice (2)
diff --git a/man2/splice.2 b/man2/splice.2
index b9b4f42..5c162e0 100644
--- a/man2/splice.2
+++ b/man2/splice.2
@@ -238,6 +238,7 @@ only pointers are copied, not the pages of the buffer.
See
.BR tee (2).
.SH SEE ALSO
+.BR copy_file_range (2),
.BR sendfile (2),
.BR tee (2),
.BR vmsplice (2)
--
2.5.3
^ permalink raw reply related [flat|nested] 19+ messages in thread* Re: [PATCH v3 10/9] copy_file_range.2: New page documenting copy_file_range()
2015-09-25 20:48 ` [PATCH v3 10/9] copy_file_range.2: New page documenting copy_file_range() Anna Schumaker
@ 2015-09-28 18:40 ` Darrick J. Wong
2015-09-28 20:42 ` Anna Schumaker
0 siblings, 1 reply; 19+ messages in thread
From: Darrick J. Wong @ 2015-09-28 18:40 UTC (permalink / raw)
To: Anna Schumaker
Cc: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
mtk.manpages, andros, hch
On Fri, Sep 25, 2015 at 04:48:16PM -0400, Anna Schumaker wrote:
> copy_file_range() is a new system call for copying ranges of data
> completely in the kernel. This gives filesystems an opportunity to
> implement some kind of "copy acceleration", such as reflinks or
> server-side-copy (in the case of NFS).
>
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> ---
> v3:
> - Added license information
> - Updated splice(2)
> - Various other edits after mailing list discussion
> ---
> man2/copy_file_range.2 | 211 +++++++++++++++++++++++++++++++++++++++++++++++++
> man2/splice.2 | 1 +
> 2 files changed, 212 insertions(+)
> create mode 100644 man2/copy_file_range.2
>
> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2
> new file mode 100644
> index 0000000..6d66d4a
> --- /dev/null
> +++ b/man2/copy_file_range.2
> @@ -0,0 +1,211 @@
> +.\"This manpage is Copyright (C) 2015 Anna Schumaker <Anna.Schumaker@Netapp.com>
> +.\"
> +.\" %%%LICENSE_START(VERBATIM)
> +.\" Permission is granted to make and distribute verbatim copies of this
> +.\" manual provided the copyright notice and this permission notice are
> +.\" preserved on all copies.
> +.\"
> +.\" Permission is granted to copy and distribute modified versions of
> +.\" this manual under the conditions for verbatim copying, provided that
> +.\" the entire resulting derived work is distributed under the terms of
> +.\" a permission notice identical to this one.
> +.\"
> +.\" Since the Linux kernel and libraries are constantly changing, this
> +.\" manual page may be incorrect or out-of-date. The author(s) assume.
> +.\" no responsibility for errors or omissions, or for damages resulting.
> +.\" from the use of the information contained herein. The author(s) may.
> +.\" not have taken the same level of care in the production of this.
> +.\" manual, which is licensed free of charge, as they might when working.
> +.\" professionally.
> +.\"
> +.\" Formatted or processed versions of this manual, if unaccompanied by
> +.\" the source, must acknowledge the copyright and authors of this work.
> +.\" %%%LICENSE_END
> +.\"
> +.TH COPY 2 2015-08-31 "Linux" "Linux Programmer's Manual"
> +.SH NAME
> +copy_file_range \- Copy a range of data from one file to another
> +.SH SYNOPSIS
> +.nf
> +.B #include <linux/copy.h>
> +.B #include <sys/syscall.h>
> +.B #include <unistd.h>
> +
> +.BI "ssize_t copy_file_range(int " fd_in ", loff_t *" off_in ", int " fd_out ",
> +.BI " loff_t *" off_out ", size_t " len \
> +", unsigned int " flags );
> +.fi
> +.SH DESCRIPTION
> +The
> +.BR copy_file_range ()
> +system call performs an in-kernel copy between two file descriptors
> +without the additional cost of transferring data from the kernel to userspace
> +and then back into the kernel.
> +It copies up to
> +.I len
> +bytes of data from file descriptor
> +.I fd_in
> +to file descriptor
> +.IR fd_out ,
> +overwriting any data that exists within the requested range of the target file.
> +
> +The following semantics apply for
> +.IR off_in ,
> +and similar statements apply to
> +.IR off_out :
> +.IP * 3
> +If
> +.I off_in
> +is NULL, then bytes are read from
> +.I fd_in
> +starting from the current file offset, and the offset is
> +adjusted by the number of bytes copied.
> +.IP *
> +If
> +.I off_in
> +is not NULL, then
> +.I off_in
> +must point to a buffer that specifies the starting
> +offset where bytes from
> +.I fd_in
> +will be read. The current file offset of
> +.I fd_in
> +is not changed, but
> +.I off_in
> +is adjusted appropriately.
> +.PP
> +
> +The
> +.I flags
> +argument can have one of the following flags set:
> +.TP 1.9i
> +.B COPY_FR_COPY
> +Copy all the file data in the requested range.
> +Some filesystems might be able to accelerate this copy
> +to avoid unnecessary data transfers.
> +.TP
> +.B COPY_FR_REFLINK
> +Create a lightweight "reflink", where data is not copied until
> +one of the files is modified.
.TP
.B COPY_FR_DEDUPE
Create a lightweight "reflink" with the same operational behavior as
COPY_FR_REFLINK, but only perform the reflink if the contents of both files'
byte ranges are identical. This flag cannot be specified with COPY_FR_COPY or
COPY_FR_REFLINK. If the ranges do not match, EILSEQ will be returned.
> +.PP
> +The default behavior
> +.RI ( flags
> +== 0) is to try creating a reflink,
> +and if reflinking fails
> +.BR copy_file_range ()
> +will fall back to performing a full data copy.
> +.SH RETURN VALUE
> +Upon successful completion,
> +.BR copy_file_range ()
> +will return the number of bytes copied between files.
> +This could be less than the length originally requested.
> +
> +On error,
> +.BR copy_file_range ()
> +returns \-1 and
> +.I errno
> +is set to indicate the error.
> +.SH ERRORS
> +.TP
> +.B EBADF
> +One or more file descriptors are not valid; or
> +.I fd_in
> +is not open for reading; or
> +.I fd_out
> +is not open for writing.
> +.TP
> +.B EINVAL
> +Requested range extends beyond the end of the source file; or the
> +.I flags
> +argument is set to an invalid value.
.TP
.B EILSEQ
The contents of both files' byte ranges did not match.
> +.TP
> +.B EIO
> +A low level I/O error occurred while copying.
> +.TP
> +.B ENOMEM
> +Out of memory.
> +.TP
> +.B ENOSPC
> +There is not enough space on the target filesystem to complete the copy.
> +.TP
> +.B EOPNOTSUPP
> +.B COPY_REFLINK
.B COPY_FR_REFLINK
or
.B COPY_FR_DEDUPE
> +was specified in
> +.IR flags ,
> +but the target filesystem does not support reflinks.
"does not support the given operation."
Otherwise you can add,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
--D
> +.TP
> +.B EXDEV
> +Target filesystem doesn't support cross-filesystem copies.
> +.SH VERSIONS
> +The
> +.BR copy_file_range ()
> +system call first appeared in Linux 4.4.
> +.SH CONFORMING TO
> +The
> +.BR copy_file_range ()
> +system call is a nonstandard Linux extension.
> +.SH EXAMPLE
> +.nf
> +#define _GNU_SOURCE
> +#include <fcntl.h>
> +#include <linux/copy.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <sys/stat.h>
> +#include <sys/syscall.h>
> +#include <unistd.h>
> +
> +loff_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
> + loff_t *off_out, size_t len, unsigned int flags)
> +{
> + return syscall(__NR_copy_file_range, fd_in, off_in, fd_out,
> + off_out, len, flags);
> +}
> +
> +int main(int argc, char **argv)
> +{
> + int fd_in, fd_out;
> + struct stat stat;
> + loff_t len, ret;
> + char buf[2];
> +
> + if (argc != 3) {
> + fprintf(stderr, "Usage: %s <source> <destination>\\n", argv[0]);
> + exit(EXIT_FAILURE);
> + }
> +
> + fd_in = open(argv[1], O_RDONLY);
> + if (fd_in == \-1) {
> + perror("open (argv[1])");
> + exit(EXIT_FAILURE);
> + }
> +
> + if (fstat(fd_in, &stat) == \-1) {
> + perror("fstat");
> + exit(EXIT_FAILURE);
> + }
> + len = stat.st_size;
> +
> + fd_out = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC, 0644);
> + if (fd_out == \-1) {
> + perror("open (argv[2])");
> + exit(EXIT_FAILURE);
> + }
> +
> + do {
> + ret = copy_file_range(fd_in, NULL, fd_out, NULL, len, COPY_FR_COPY);
> + if (ret == \-1) {
> + perror("copy_file_range");
> + exit(EXIT_FAILURE);
> + }
> +
> + len \-= ret;
> + } while (len > 0);
> +
> + close(fd_in);
> + close(fd_out);
> + exit(EXIT_SUCCESS);
> +}
> +.fi
> +.SH SEE ALSO
> +.BR splice (2)
> diff --git a/man2/splice.2 b/man2/splice.2
> index b9b4f42..5c162e0 100644
> --- a/man2/splice.2
> +++ b/man2/splice.2
> @@ -238,6 +238,7 @@ only pointers are copied, not the pages of the buffer.
> See
> .BR tee (2).
> .SH SEE ALSO
> +.BR copy_file_range (2),
> .BR sendfile (2),
> .BR tee (2),
> .BR vmsplice (2)
> --
> 2.5.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-api" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 19+ messages in thread* Re: [PATCH v3 10/9] copy_file_range.2: New page documenting copy_file_range()
2015-09-28 18:40 ` Darrick J. Wong
@ 2015-09-28 20:42 ` Anna Schumaker
0 siblings, 0 replies; 19+ messages in thread
From: Anna Schumaker @ 2015-09-28 20:42 UTC (permalink / raw)
To: Darrick J. Wong
Cc: linux-nfs, linux-btrfs, linux-fsdevel, linux-api, zab, viro, clm,
mtk.manpages, andros, hch
On 09/28/2015 02:40 PM, Darrick J. Wong wrote:
> On Fri, Sep 25, 2015 at 04:48:16PM -0400, Anna Schumaker wrote:
>> copy_file_range() is a new system call for copying ranges of data
>> completely in the kernel. This gives filesystems an opportunity to
>> implement some kind of "copy acceleration", such as reflinks or
>> server-side-copy (in the case of NFS).
>>
>> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
>> ---
>> v3:
>> - Added license information
>> - Updated splice(2)
>> - Various other edits after mailing list discussion
>> ---
>> man2/copy_file_range.2 | 211 +++++++++++++++++++++++++++++++++++++++++++++++++
>> man2/splice.2 | 1 +
>> 2 files changed, 212 insertions(+)
>> create mode 100644 man2/copy_file_range.2
>>
>> diff --git a/man2/copy_file_range.2 b/man2/copy_file_range.2
>> new file mode 100644
>> index 0000000..6d66d4a
>> --- /dev/null
>> +++ b/man2/copy_file_range.2
>> @@ -0,0 +1,211 @@
>> +.\"This manpage is Copyright (C) 2015 Anna Schumaker <Anna.Schumaker@Netapp.com>
>> +.\"
>> +.\" %%%LICENSE_START(VERBATIM)
>> +.\" Permission is granted to make and distribute verbatim copies of this
>> +.\" manual provided the copyright notice and this permission notice are
>> +.\" preserved on all copies.
>> +.\"
>> +.\" Permission is granted to copy and distribute modified versions of
>> +.\" this manual under the conditions for verbatim copying, provided that
>> +.\" the entire resulting derived work is distributed under the terms of
>> +.\" a permission notice identical to this one.
>> +.\"
>> +.\" Since the Linux kernel and libraries are constantly changing, this
>> +.\" manual page may be incorrect or out-of-date. The author(s) assume.
>> +.\" no responsibility for errors or omissions, or for damages resulting.
>> +.\" from the use of the information contained herein. The author(s) may.
>> +.\" not have taken the same level of care in the production of this.
>> +.\" manual, which is licensed free of charge, as they might when working.
>> +.\" professionally.
>> +.\"
>> +.\" Formatted or processed versions of this manual, if unaccompanied by
>> +.\" the source, must acknowledge the copyright and authors of this work.
>> +.\" %%%LICENSE_END
>> +.\"
>> +.TH COPY 2 2015-08-31 "Linux" "Linux Programmer's Manual"
>> +.SH NAME
>> +copy_file_range \- Copy a range of data from one file to another
>> +.SH SYNOPSIS
>> +.nf
>> +.B #include <linux/copy.h>
>> +.B #include <sys/syscall.h>
>> +.B #include <unistd.h>
>> +
>> +.BI "ssize_t copy_file_range(int " fd_in ", loff_t *" off_in ", int " fd_out ",
>> +.BI " loff_t *" off_out ", size_t " len \
>> +", unsigned int " flags );
>> +.fi
>> +.SH DESCRIPTION
>> +The
>> +.BR copy_file_range ()
>> +system call performs an in-kernel copy between two file descriptors
>> +without the additional cost of transferring data from the kernel to userspace
>> +and then back into the kernel.
>> +It copies up to
>> +.I len
>> +bytes of data from file descriptor
>> +.I fd_in
>> +to file descriptor
>> +.IR fd_out ,
>> +overwriting any data that exists within the requested range of the target file.
>> +
>> +The following semantics apply for
>> +.IR off_in ,
>> +and similar statements apply to
>> +.IR off_out :
>> +.IP * 3
>> +If
>> +.I off_in
>> +is NULL, then bytes are read from
>> +.I fd_in
>> +starting from the current file offset, and the offset is
>> +adjusted by the number of bytes copied.
>> +.IP *
>> +If
>> +.I off_in
>> +is not NULL, then
>> +.I off_in
>> +must point to a buffer that specifies the starting
>> +offset where bytes from
>> +.I fd_in
>> +will be read. The current file offset of
>> +.I fd_in
>> +is not changed, but
>> +.I off_in
>> +is adjusted appropriately.
>> +.PP
>> +
>> +The
>> +.I flags
>> +argument can have one of the following flags set:
>> +.TP 1.9i
>> +.B COPY_FR_COPY
>> +Copy all the file data in the requested range.
>> +Some filesystems might be able to accelerate this copy
>> +to avoid unnecessary data transfers.
>> +.TP
>> +.B COPY_FR_REFLINK
>> +Create a lightweight "reflink", where data is not copied until
>> +one of the files is modified.
>
> .TP
> .B COPY_FR_DEDUPE
> Create a lightweight "reflink" with the same operational behavior as
> COPY_FR_REFLINK, but only perform the reflink if the contents of both files'
> byte ranges are identical. This flag cannot be specified with COPY_FR_COPY or
> COPY_FR_REFLINK. If the ranges do not match, EILSEQ will be returned.
>
>> +.PP
>> +The default behavior
>> +.RI ( flags
>> +== 0) is to try creating a reflink,
>> +and if reflinking fails
>> +.BR copy_file_range ()
>> +will fall back to performing a full data copy.
>> +.SH RETURN VALUE
>> +Upon successful completion,
>> +.BR copy_file_range ()
>> +will return the number of bytes copied between files.
>> +This could be less than the length originally requested.
>> +
>> +On error,
>> +.BR copy_file_range ()
>> +returns \-1 and
>> +.I errno
>> +is set to indicate the error.
>> +.SH ERRORS
>> +.TP
>> +.B EBADF
>> +One or more file descriptors are not valid; or
>> +.I fd_in
>> +is not open for reading; or
>> +.I fd_out
>> +is not open for writing.
>> +.TP
>> +.B EINVAL
>> +Requested range extends beyond the end of the source file; or the
>> +.I flags
>> +argument is set to an invalid value.
>
> .TP
> .B EILSEQ
> The contents of both files' byte ranges did not match.
>
>> +.TP
>> +.B EIO
>> +A low level I/O error occurred while copying.
>> +.TP
>> +.B ENOMEM
>> +Out of memory.
>> +.TP
>> +.B ENOSPC
>> +There is not enough space on the target filesystem to complete the copy.
>> +.TP
>> +.B EOPNOTSUPP
>> +.B COPY_REFLINK
>
> .B COPY_FR_REFLINK
> or
> .B COPY_FR_DEDUPE
>
>> +was specified in
>> +.IR flags ,
>> +but the target filesystem does not support reflinks.
>
> "does not support the given operation."
>
> Otherwise you can add,
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Thanks, Darrick!
I've added in your suggestions (and also renamed COPY_FR_DEDUPE -> COPY_FR_DEDUP). I'll send out a v4 tomorrow morning, once I see if any other comments trickle in.
Anna
>
> --D
>
>> +.TP
>> +.B EXDEV
>> +Target filesystem doesn't support cross-filesystem copies.
>> +.SH VERSIONS
>> +The
>> +.BR copy_file_range ()
>> +system call first appeared in Linux 4.4.
>> +.SH CONFORMING TO
>> +The
>> +.BR copy_file_range ()
>> +system call is a nonstandard Linux extension.
>> +.SH EXAMPLE
>> +.nf
>> +#define _GNU_SOURCE
>> +#include <fcntl.h>
>> +#include <linux/copy.h>
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <sys/stat.h>
>> +#include <sys/syscall.h>
>> +#include <unistd.h>
>> +
>> +loff_t copy_file_range(int fd_in, loff_t *off_in, int fd_out,
>> + loff_t *off_out, size_t len, unsigned int flags)
>> +{
>> + return syscall(__NR_copy_file_range, fd_in, off_in, fd_out,
>> + off_out, len, flags);
>> +}
>> +
>> +int main(int argc, char **argv)
>> +{
>> + int fd_in, fd_out;
>> + struct stat stat;
>> + loff_t len, ret;
>> + char buf[2];
>> +
>> + if (argc != 3) {
>> + fprintf(stderr, "Usage: %s <source> <destination>\\n", argv[0]);
>> + exit(EXIT_FAILURE);
>> + }
>> +
>> + fd_in = open(argv[1], O_RDONLY);
>> + if (fd_in == \-1) {
>> + perror("open (argv[1])");
>> + exit(EXIT_FAILURE);
>> + }
>> +
>> + if (fstat(fd_in, &stat) == \-1) {
>> + perror("fstat");
>> + exit(EXIT_FAILURE);
>> + }
>> + len = stat.st_size;
>> +
>> + fd_out = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC, 0644);
>> + if (fd_out == \-1) {
>> + perror("open (argv[2])");
>> + exit(EXIT_FAILURE);
>> + }
>> +
>> + do {
>> + ret = copy_file_range(fd_in, NULL, fd_out, NULL, len, COPY_FR_COPY);
>> + if (ret == \-1) {
>> + perror("copy_file_range");
>> + exit(EXIT_FAILURE);
>> + }
>> +
>> + len \-= ret;
>> + } while (len > 0);
>> +
>> + close(fd_in);
>> + close(fd_out);
>> + exit(EXIT_SUCCESS);
>> +}
>> +.fi
>> +.SH SEE ALSO
>> +.BR splice (2)
>> diff --git a/man2/splice.2 b/man2/splice.2
>> index b9b4f42..5c162e0 100644
>> --- a/man2/splice.2
>> +++ b/man2/splice.2
>> @@ -238,6 +238,7 @@ only pointers are copied, not the pages of the buffer.
>> See
>> .BR tee (2).
>> .SH SEE ALSO
>> +.BR copy_file_range (2),
>> .BR sendfile (2),
>> .BR tee (2),
>> .BR vmsplice (2)
>> --
>> 2.5.3
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-api" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
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